This invention relates to improvements in a cooling device for a semiconductor device utilizing the heat transfer due to boiling of a condensible coolant such as FREON (trade mark).
It is well known that cooling systems utilizing the heat transfer resulting from boiling of the condensible coolant are distinctively excellent in cooling characteristics as compared with cooling systems employed for long time to cool electric devices. Recently there are being developed cooling devices for electric devices utilizing the high heat transfer due to boiling. For example, U.S. patent application Ser. No. 557,892 entitled "Vapor Cooling Device", filed by T. Suzuki et al. on Mar. 12, 1975 and assigned to the same assignee as the present application discloses a vapor cooling device comprising a coolant reservoir filled with an amount of a condensible coolant in its liquid phase, a plurality of semiconductor elements alternating in compressive contact relationship hollow heat dissipation blocks and disposed below the coolant reservoir, one connection tube for connecting the coolant reservoir to each of the hollow heat dissipation blocks to fill it with the liquid coolant, and a condenser disposed above the coolant reservoir to be put in fluid communication with the latter. Also U.S. patent application Ser. No. 559,393 entitled "Vapor Cooling Device For Electric Device", filed by G. Kobayashi et al. on Mar. 17, 1975 and assigned to the same assignee as the present application teaches an auxiliary tube disposed within a connection tube for connecting a coolant reservoir with a condensible coolant in its liquid phase to a coolant container filled with the liquid coolant acting as a heat dissipation block and having both ends opening in the reservoir and container respectively.
In vapor cooling devices for semiconductor devices produced by incorporating the teachings of the last-mentioned application into vapor cooling devices disclosed in the first-mentioned application, the auxiliary tube has been used only to supply the liquid coolant to the hollow heat dissipation block resulting in a great improvement in cooling characteristic. However it has been found that a change in quantity of heat generated by the semiconductor elements may vary the temperature distribution of the liquid coolant adjacent to the upper open ends of the auxiliary tubes so that that portion of the liquid coolant filling any one or more of the heat dissipation blocks can boil without heat applied thereto accompanied by boiling of the liquid coolant passing through the associated auxiliary tube or tubes, and hence the formation of bubbles therein. Under these circumstances, it would become difficult to supply the liquid coolant to that heat dissipation block in which the coolant is boiling leading to a danger that the liquid coolant becomes insufficient in amount within such a heat dissipation block.
Accordingly it is an object of the present invention to avoid this danger.
It is another object of the present invention to provide a new and improved vapor cooling device for a semiconductor device distinctively excellent in cooling capability.